Phytoremediation of salt impacted soils

对于上游石油和天然气工业来说，土壤中氯化钠(盐)水平升高的问题与土壤的石油污染一样重要。受盐分影响的土壤的修复已被证明是困难和昂贵的，因为缺乏一种通用的、允许就地或现场修复的技术。植物修复(基于植物的生物修复)比传统的去除或基于化学的修复方法具有许多优点。不幸的是，盐胁迫通常会导致乙烯(一种植物应激激素)的产生增加，并导致植物生长减慢。如果没有高水平的生物量，就不可能实现可接受的补救措施。我们最近开发的用于石油修复的多进程植物修复系统(MPPS)在盐渍土壤修复方面具有潜在的应用前景。这种生物系统的一个关键特征是利用植物生长促进根际细菌(PGPR)来缓解植物胁迫。这些PGPR消耗植物激素乙烯的前体，从而减少植物中乙烯的生物合成。因此，可以在受盐分影响的土壤上实现植物的蓬勃生长，并应有助于修复土壤中的盐分。在我们的中试实验中，结果最有希望的PGPR是两株恶臭假单胞菌(UW3和UW4)。这些是我们目前用于石油修复的自然产生的PGPR菌株。它们被列在加拿大环境部的安全和非致病微生物名单上。总的来说，我们观察到植物萌发和可归因于PGPR的植物总生物量至少增加了100%。我们已经在温室实验中对盐分修复进行了检测。在这个节骨眼上，结果还没有定论。为了准确评估盐碱地修复，我们需要更多的数据和更长的生长期。今年冬天在温室里，我们将在更长的时间内种植植物，以便在每次实验中进行更多的补救。春季，我们将在艾伯塔省3个受盐分影响的地点进行野外实验。这些地点与上游石油和天然气行业有关，有不同程度的盐污染。

The problem of elevated sodium chloride (salt) levels in soils is as important as petroleum contamination of soils for the upstream oil and gas industry. The remediation of salt impacted soils has proven difficult and costly due to the absence of a technology that is versatile and allows for in-situ or on-site remediation. Phytoremediation (plant-based bioremediation) offers many advantages over conventional removal or chemical-based remediation methods. Unfortunately, salt stress often leads to increased production of ethylene, a plant stress hormone, and results in diminished plant growth. Without high levels of biomass acceptable rates of remediation can not be achieved. Our recently developed multi-process phytoremediation system (MPPS) used for petroleum remediation has potential applications for remediation of salt impacted soils. A key feature of this biological system is the alleviation of plant stress by using plant growth promoting rhizobacteria (PGPR). These PGPR consume the precursor to the plant hormone ethylene, thus decreasing ethylene biosynthesis in plants. As a result, vigorous plant growth on salt impacted soils can be achieved, and should facilitate remediation of salt from the soil. In our pilot experiments, the PGPRs with the most promising results were two Pseudomonas putida strains (UW3 and UW4). These are the naturally occurring strains of PGPR that we currently use for petroleum remediation. They are on Environment Canada's list of safe and non-pathogenic microbes. In general, we are observing at least a 100 % increase in plant germination and total plant biomass attributable to PGPR. We have assayed for salt remediation in a greenhouse experiment. The results are inconclusive at this juncture. To accurately assess salt remediation we need more data and longer growth periods. This winter in the greenhouse, we will grow plants for longer time periods, allowing more remediation to occur within each experiment. In the Spring, we will proceed with field experiments at 3 salt-impacted sites in Alberta. These sites are associated with the upstream oil and gas industry, and have varying levels of salt contamination.